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rvg8tor
Joined: 06 Apr 2009
Posts: 50
Location: Olympia, WA
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 Posted: Sun Sep 20, 2009 12:45 pm Post subject: P-mag Internal Power Test |
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I am getting my wiring started and have a question on how some of you with P-Mags wired your systems. There are two tests for th P-Mag as I understand things. One is just like a traditional magneto check, you turn off (ground the p-lead) and check for mag drop. The other check for a P-Mag is to turn off the 12v power to the P-Mag to check that the internal alternator keeps the magneto running. The check of the internal alternator does not seem like something that needs to be check each flight. I am considering just pulling the CB for each P-Mag to make this check rather than wiring a switch to serve this purpose.
What have others done with regard to this, I don't want to use a switched breaker, I will just add the switch if it is required. My thinking is to just pull the breaker. We pull breaker on the B-767 at the end of each flight to turn some equipment off while the plane sits between flights, so I don't think there is an issue of waring out a breaker. Thanks for any pointers.
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_________________
Mike "Nemo" Elliott
RV-8A QB (Engine)
www.mykitlog.com/rvg8tor |
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dalamphere(at)comcast.net
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nuckolls.bob(at)aeroelect
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| Posted: Sun Sep 20, 2009 5:13 pm Post subject: P-mag Internal Power Test |
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At 03:45 PM 9/20/2009, you wrote:
| Quote: |
I am getting my wiring started and have a question on how some of
you with P-Mags wired your systems. There are two tests for th
P-Mag as I understand things. One is just like a traditional
magneto check, you turn off (ground the p-lead) and check for mag
drop. The other check for a P-Mag is to turn off the 12v power to
the P-Mag to check that the internal alternator keeps the magneto
running. The check of the internal alternator does not seem like
something that needs to be check each flight. I am considering just
pulling the CB for each P-Mag to make this check rather than wiring
a switch to serve this purpose.
What have others done with regard to this, I don't want to use a
switched breaker, I will just add the switch if it is required. My
thinking is to just pull the breaker. We pull breaker on the B-767
at the end of each flight to turn some equipment off while the plane
sits between flights, so I don't think there is an issue of waring
out a breaker. Thanks for any pointers.
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What you've proposed is consistent with Emagair's
recommendations. In fact, Figure Z13/8 was crafted
with a similar philosophy.
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8Q.pdf
Note that with ship's power taken through
a fuse from the main bus, the internal power
source integrity can be verified occasionally
by checking engine operations on the p-mag while
the main bus is down. Easy to do under comfortable
conditions and only occasionally.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
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andrewbutler(at)ireland.c
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| Posted: Mon Sep 21, 2009 4:22 am Post subject: P-mag Internal Power Test |
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Hi Mike,
Here is some additional info. I got from Emagair directly last year when researching the units. I personally have wired up according to Z13, with two switches for each unit, p-lead and power. I don't have CBs for the circuits, rather fuses.
Regards, Andrew.
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From: info(at)emagair.com [mailto:info(at)emagair.com]
Sent: 09 May 2008 16:57
To: Butler, Andrew
Subject: RE: Startup Checks
Andrew:
When an ignition is first powered up it has to wake up, load the operating code, track engine position, determine when the next spark even needs to happen, and finally trigger that spark event. If you power up while the engine is running all this has to happen very quickly. Since P models make their own power (as long as the engine is running), you cannot shut down the processor. You can turn both the p-lead and the 12 supply OFF and it will still be "awake" doing its business as usual, waiting to resume firing as soon as the p-lead is ungrounded. With E models, however, you can power them OFF when running, and the ignition (truly) will go dark - still no problem. Powering the E model OFF is not the issue. It's when you 1) power an E model ON (while the engine is running) and 2) with the p-lead ungrounded that you are asking it to instantaneously wake up and start firing as described above. The condition can be avoided (if encountered) by making sure the p-lead is grounded (OFF) before powering (12 volt) ON an E model ignition while the engine is running.
Even so, if this happens, we aren't predicting disaster. It will probably resume operation just fine, but there is no reason to do it in the first place - that's all.
I don't recall any customers (yet) in Ireland - congratulations, you'll be number 1.
Kindest Regards,
Brad Dement
E-MAG Ignitions
2014 Greg Street Box 112
Azle, Texas 76020
(817) 444-5310
From: Butler, Andrew [mailto:andrew.butler(at)nuigalway.ie]
Sent: Friday, May 09, 2008 10:29 AM
To: info(at)emagair.com
Subject: RE: Startup Checks
Thanks very much Brad.
· What is the logic behind not switching off power to an E-MAG while the engine is running? I am assuming that switching off power is okay, that it is switching power back on while the engine is turning that is the problem. What exactly is the event sequence associated with switching on power while the engine is turning that is problematic?
· Why is it problematic to turn power on while the P-MAG is “live” i.e ungrounded?
I am not installing a rotary key switch, rather an individual power switch for each ignition. It appears that I will need a two position switch that allows me to control access to power and ground individually.
Cheers, Andrew.
RV71700
Galway, Ireland.
From: info(at)emagair.com [mailto:info(at)emagair.com]
Sent: 08 May 2008 17:07
To: Butler, Andrew
Subject: RE: Startup Checks
Hi Andrew:
Thanks for considering us for your project.
The ignition check for E-MAG ignitions is very similar to that of magnetos. You'll do your regular L/R (p-lead) check to make sure both ignitions operate. The only difference is that for each P model ignition you have installed (one or both) you'll add one additional sequence. While switched to the individual P model(s), simply turn OFF the 12 volt power that feeds that ignition for a few seconds to verify the engine continues to run. If the engine runs, the internal alternator is operating. If the engine quits, the alternator is not working. The engine speed should be 1000 rpm or greater when you do this check.
There is no need to do this test with an E model as they don't have an alternator. The L/R test is a p-lead (ON/OFF) test applicable to both E and P models. The 12 power (ON/OFF) test is applicable to P models only, and we discourage doing it with E models, so the FAQ you refer to is not in conflict with the pre-flight ignition tests.
The Installation and Operating Guide also has some recommendations on starting with our equipment - see Downloads page on our web site.
Don't hesitate to call or drop us a note if you have any other questions.
Kindest Regards,
Brad Dement
E-MAG Ignitions
2014 Greg Street Box 112
Azle, Texas 76020
(817) 444-5310
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nuckolls.bob(at)aeroelect
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| Posted: Mon Sep 21, 2009 6:15 am Post subject: P-mag Internal Power Test |
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At 06:47 AM 9/21/2009, you wrote:
| Quote: |
<andrewbutler(at)ireland.com>
Hi Mike,
Here is some additional info. I got from Emagair directly last year
when researching the units. I personally have wired up according to
Z13, with two switches for each unit, p-lead and power. I don't have
CBs for the circuits, rather fuses.
Regards, Andrew.
|
<snip>
Thanks for that expansion Andrew. I had a similar
dissertation from the guys at Emagair but couldn't
lay my hands on it last night.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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